A conventional switch of the type of being pressed to be turned on or off has a locking mechanism for locking a contact holder in a pressed-in position and unlocking the holder out of the position.
The locking mechanism is constituted by a heart-shaped cam groove provided in the side of the contact holder, and a locking pin supported at a bottom portion thereof by the casing of the switch and fitted at a tip of the pin in the cam groove so that the pin slide in the cam groove relative to the contact holder as the holder is moved. The tip of the locking pin is urged to the bottom or one side of the cam groove by a spring.
When the contact holder is pressed out of the original position thereof, the tip of the locking pin slides in the cam groove. When the pressing of the contact holder is ceased, the tip of the locking pin is engaged into the locking part of the cam groove so that the contact holder is locked in the pressed-in position thereof. When the contact holder is pressed again, the tip of the locking pin slides in the cam groove and is disengaged out of the locking part thereof. When the latter pressing of the contact holder is ceased, the holder is returned to its original position along with the sliding of the tip of the locking pin in the cam groove.
Since the tip of the locking pin of the conventional switch is always urged to the cam groove by the spring, the resistance to the sliding of the pin in the cam groove is so high that the manipulating property of the switch is low. This is a problem. Further, a collision noise would be generated when the tip of the locking pin falls down the stepped portion of the cam groove. This is another problem.